1. Field of the Invention
This invention is directed to a stiffener for a printed circuit (PC) board. More particular, the invention concerns an easily detachable stiffener which prevents physical vibrations of a PC board and resultant breaking of the PC board interconnect metallization tracings and/or the solder joints between the conductive lead pin fingers of an integrated circuit chip and a conductive via or socket in a PC board.
2. Prior Art
The PC boards currently utilized in the electronic field, particularly for large computers and control equipment for many industrial, aerospace and other transportation applications, are made of relatively thin laminated plastic substrates of G-10 material typically from about 1.2 mm to about 3.0 mm in thickness. As a PC board becomes larger in area and in span between support points the board becomes increasingly more flexible and subject to vibrational damage, dependent primarily on the PC board environment. Amplitudes of up to plus or minus 10 mm have been observed at the center of typical PC boards of a 365 cm by 400 cm rectangular configuration. Metal stiffening frames have been utilized extending peripherally around the PC board. While such frames stiffen the peripheral edges of the PC board, the center of the board still may vibrate substantially from applied vibrational forces. For example, in an aerospace environment such as an aircraft upon take-off, from an airfield or by ship catapult, or under maneuvering exercises, there is much flexing and vibration aboard the craft. While stiffening bars have been proposed and tried they normally add too much additional weight and size. They require real estate for mounting, surrendering space which could be used for mounting electronic components. Such bars are normally of metal to give high stiffness, resulting in possible shorts across electrical connections during vibrational occurrences. Further, it is normally difficult to obtain quick access to the PC board for repairs or testing when previous attempts have been made to lock the board in place against vibration. While PC boards have been made more rugged by using thicker substrates or utilizing integral stiffeners these add size and/or weight, which factors are at a premium in aerospace, man transportable and most other applications.